The Origins of the Killer Asteroid! ... or Comet!?

We all know the story of how the dinosaurs went extinct. I will summarize it for you if you don’t know. Pretty much, there was a giant asteroid that struck Mexico and created a massive creator that was later dubbed the Chicxulub Crater. While only a small percentage were killed by the initial impact, there were many repercussions. Dust was kicked around everywhere blocking the Sun. This also caused volcanoes to erupt, which also helped to block the sunlight. Because the sunlight was blocked, plants started to die. Herbivorous dinosaurs died and carnivorous dinosaurs began to follow suit. Now, they live on as birds and the Jurassic Park series. But scientists still don’t know where the killer asteroid originated from.

Render of Comet Making Its Way to Earth

A 2007 report first said that the asteroid that created the Chicxulub crater originated from the asteroid belt. The authors said that over 160 million years ago, there was a collision in the asteroid belt that created the Baptistina family of asteroids. The Baptistina is the largest family of asteroids, with one of surviving members being 298 Baptistina. To put into perspective how large they are, 298 Baptistina has measured about 13 to 30 km (8 to 19 mi) in diameter. The theory proposed that the “Chicxulub asteroid” was part of the Baptistina family. This is supported by the size of the Chicxulub crater which is a whopping 150 km (93 mi) in diameter and 20 km (12 mi) deep. There is also a large amount of carbonaceous material present in microscopic fragments in the impact site, which is common in the Baptistina family. Another theory from 2010 said that the asteroid was a member of the Flora family of asteroids because of the possibility of it being a remnant cohort of the K/Pg impactor.

298 Baptistina

However, a new theory proposed last week hypothesizes that the impactor was not an asteroid, but a piece of a comet from the Oort cloud. Comets are massive bodies of ice and the Oort clouds are located at the edge of our solar system and are mostly made up of icy planetesimals. Comets mostly originate from this region and have very long orbital periods. In fact, comets in the Oort cloud take hundreds of years to orbit the Sun. Interestingly, earlier studies have shown that the chances of a comet passing into the path of the Earth is very very low. This removes comets as the culprit of the extinction of dinosaurs. However, with a little gravitational push and pull, the trajectory of comets can be changed. That is what is being proposed in this new theory.

Artist's Representation of the Oort Cloud

The theory is stating that the gravitational field of Jupiter redirected the comet for a direct trajectory to Earth. Scientific models and simulations are able to back this theory up. In fact, the study showed that 20% of comets from the Oort cloud are redirected by Jupiter’s gravitational field and makes them 10 times more likely to hit Earth. However, it is still a very low number. These comets that have a new trajectory are called “sun-grazers” as they pass relatively close to the Sun. When a comet is closer to the Sun, the gravity and heat of the sun break up the comets, causing them to be harmless pieces of rock floating in our solar system. However, this wasn’t the case for the Chicxulub impactor as it was responsible for the extinction of the dinosaurs. The new model also shows that this type of event can happen every 250 million to 730 million years.

Render of the Impact
that Killed the Dinosaurs

We have had close encounters with comets before, but none have been threatening. One example was the NEOWISE comet that passed by the Earth in July. I wrote an article about it, so click here to check it out. Whatever hit the Earth on that fateful day 65 million years ago was very dangerous and has the potential to destroy the human race as we know it. To ever prevent this from happening, scientists and researchers all over the world are trying to find the next big asteroid and are developing methods to destroy or redirect these killer asteroids. Let’s hope that we find it before it finds us.

Chicxulub Crater Today

Sources:

“298 Baptistina.” Wikipedia, Wikimedia Foundation, 5 June 2020, en.wikipedia.org/wiki/298_Baptistina. 

“Chicxulub Crater.” Wikipedia, Wikimedia Foundation, 22 Feb. 2021, en.wikipedia.org/wiki/Chicxulub_crater#Astronomical_origin_of_impactor. 

“Oort Cloud.” Wikipedia, Wikimedia Foundation, 13 Feb. 2021, en.wikipedia.org/wiki/Oort_cloud. 

Pappas, Stephanie. “Dinosaur-Killing Space Rock May Have Originated at the Edge of the Solar System.” Space.com, Space, 22 Feb. 2021, www.space.com/dinosaur-killing-comet-oort-cloud. 

Pradhan, Arnav. NEOWISE Was Wise to Travel by Earth in July, Blogger, 21 Dec. 2020, www.arnavpradhan.com/2020/12/neowise-was-wise-to-travel-by-earth-in.html. 

Wei-Haas, Maya. “Last Day of the Dinosaurs' Reign Captured in Stunning Detail.” Science, National Geographic, 10 Feb. 2021, www.nationalgeographic.com/science/article/last-day-dinosaurs-reign-captured-stunning-detail.